3 of 3 people found this helpful
If you are using an AF Expression Analysis, you could add a named intermediate variable calculation at the beginning of your analysis to do this:
If 'Attribute' = -123456789 Then PrevVal('Attribute', '*') Else 'Attribute'
You would then use the this named intermediate variable to access the validated value in the remaining steps of your calculation.
If this particular tag value is used across multiple calculations, then you would need to write this particular calculation result to a 'validated' tag, and use the validated tag as an input to the other calculations, rather than the 'raw' tag.